Here's a simple one about a new feature added in 10.4.7. In Disk Utility at the bottom of the window (below S.M.A.R.T. Status), you can now see the Partition Scheme. This is only visible when you have the hard drive itself selected, not any partitions on the drive.

For PowerPC Macs, you'll see Apple Partition Map; on Intel Macs, it will be GUID Partition Table.